Despite solid evidence (and frequent discussion on this blog) showing conclusively that whole host of factors contribute to excessive weight gain,currently, responsibility for maintaining a healthy weight rests solely with the individual. Therefore, people may think that stigmatising those who ‘refuse’ to conform to the ‘societal imperative’ is justified . Some may go even further and claim that stigmatising overweight and obese people would encourage them to lose weight. However, when our researchers looked at the scientific literature surrounding stigma and weight loss, there was little evidence showing whether this was actually true.

To find out whether weight and the experience of stigma are related in some way, researchers from our department looked at data from 2,944 UK adults over four years who participated in the English Longitudinal Study of Ageing (ELSA), a study of adults aged 50 or older. Participants are weighed and measured every four years, and asked questions on a range of topics every two years.

To assess stigma, participants were asked how often they encounter five discriminatory situations: ‘In your day-to-day life, how often have any of the following things happened to you: 1) You are treated with less respect or courtesy; 2) you receive poorer service than other people in restaurants and stores; 3) people act as if they think you are not clever; 4) you are threatened or harassed; 5) you receive poorer service or treatment than other people from doctors or hospitals. Responses ranged from ‘never’ to ‘almost every day’. Participants who reported discrimination in any of the situations were asked to indicate the reason(s) they attributed their experience to from a list of options including weight, age, gender, and race. The researchers considered participants who attributed experiences of discrimination to their weight as cases of perceived weight discrimination. Because many participants reported never experiencing discrimination, the researchers divided responses to indicate whether or not respondents had ever experienced discrimination in any domain (never vs. all other options).

Of the 2,944 eligible participants in the study, 5% reported weight discrimination. This ranged from less than 1% of those in the ‘normal weight’ category to 36% of those classified as ‘‘morbidly obese’. Men and women reported similar levels of weight discrimination.

However, those who reported experiencing weight discrimination gained more weight than those who did not over the 4-year period. On average, after taking baseline differences in BMI, gender, age and personal wealth into account, people who reported weight discrimination gained 0.95kg whereas those who did not lost 0.71kg, a difference of 1.66kg.

However, because this study looked only at the relationship of perceived stigma and weight gain, we cannot conclude that stigma caused weight gain – it could also be that weight gain increased perceived stigma, or that a third factor influenced both weight gain and stigma. To conclusively establish whether stigma indeed causes weight gain, we would have to run a controlled experiment with at least two groups of similarly overweight people, where one group is subjected to stigma over a period of time, and the other one is not, and then measure their weight at the end of the study. Of course, such an experiment would be highly unethical, given the damaging effects of stigma on psychological health. Another limitation of this study was that discrimination was assessed two years after the initial weight measurements and two years before the final measurements, although the researchers controlled statistically for this.

However, regardless of its limitations, this study showed that weight discrimination is definitely not associated with weight loss. This means that there was no evidence for the idea that stigmatising overweight and obese individuals would motivate them to lose weight. in many cases, it may even hinder weight loss. Therefore, we should work towards removing prejudice and blame from weight loss advice and should focus on positively supporting those who are trying to lose weight. One way may be to teach active coping strategies and increasing acceptance-based elements into weight loss programmes because this has had some promising effects. Furthermore, we will need to continue highlighting the complex causes of obesity rather than relying on simplistic representations, and increase work to acknowledge and address weight-related stigma, to make the ‘last socially acceptable form of prejudice’ unacceptable.

A heartier appetite is linked to more rapid infant growth and to genetic predisposition to obesity, according to two studies recently published by our researchers in the journal JAMA Pediatrics.

Although it is clear that some people seem to struggle much more than others to keep a healthy weight, so far it has been less obvious why this is the case.Researchers from our department have now shown that differences in appetite, and especially lower satiety sensitivity (a reduced urge to eat in response to internal ‘fullness’ signals) and higher food responsiveness (an increased urge to eat in response to the sight or smell of nice food) may hold the key to unhealthy weight gain.

In the first study, the researchers showed that infants with a heartier appetite grew more rapidly up to age 15 months, potentially putting them at increased risk of obesity.

Our researchers used data from non-identical, same-sex twins born in the UK in 2007. As we have previously discussed, twins are a good model to study differences between people because they are born at the same time, and usually grow up in a very similar environment.

Twin pairs were selected that differed in measures of satiety responsiveness (172 pairs) and food responsiveness (121 pairs) at 3 months, and their growth up to age 15 months was compared. Within pairs, the infant who was more food responsive or less satiety responsive grew faster than their co-twin.

The more food responsive twin was 654g heavier (1.4lbs) than their co-twin at six months and 991g heavier (2.1lbs) at 15 months. The less satiety responsive twin was 637g heavier (1.4lbs) than their co-twin at six months and 918g heavier (2lbs) at 15 months.

This is a considerable weight difference for children of this age, and represents a 10% weight difference. Over time as weight differences increase, these children are at a higher risk of obesity.Therefore, it might be beneficial to watch out if a child seems to have difficulties filling up, or seems to be somewhat responsive to food cues in the environment.

However, this first study could not tell whether children with low satiety responsiveness or high food responsiveness would continue to be heavier; nor did it tell about possible underlying genetics.

Therefore, the second study was set up to shed more light on how appetite, and especially low satiety responsiveness, acts as one of the mechanisms underlying genetic predisposition to obesity.For this study, our researchers collaborated with a team from King’s College, London.

The researchers accessed data from over 2,000 unrelated 10-year-old children born in the UK between 1994 and 1996. First, the team created a combined genetic risk score (polygenic risk score) for each child.To do this, they added up the number of higher risk versions of 28 obesity-related genes (each gene has 2 versions, as we all get one version from Mum and one version from Dad). A higher polygenic risk score meant that the child was at higher genetic risk of obesity.

The researchers then looked at how the children’s genetic risk scores related not only to their satiety responsiveness, but also to their body fatness (measured using body mass index and waist circumference).

As expected, they found that children at a higher genetic risk of obesity had higher BMIs (which is a measure of weight status) and a larger waist circumference.This finding was in line with what we already know about the genetic basis of obesity (see our other blogpost).But key to our study was showing that they were also less sensitive to satiety.

This finding suggests that satiety responsiveness is one of the mechanisms through which ‘obesity genes’ influence body weight.Therefore, it might indeed be beneficial to teach children with lower satiety sensitivity techniques that might improve their fullness signals when eating. Advice to parents on encouraging children to eat more slowly, having a ‘no second helpings’ policy, and keeping tempting treats out of sight between meals could help. Knowing that there are genetic influences on appetite might help parents understand and accept that children differ, and that some need more support in learning the boundaries of appropriate eating.

Likewise, for adults who feel they have difficulty controlling their weight, it might be beneficial to understand that differences in appetite might be one contributing reason.Techniques that help adults to ‘feel’ the fullness, such as ‘mindful eating’ and portion control may be useful aides in ‘outsmarting’ any biological tendencies to eat too much.

If you thought that the stresses of present-picking, turkey-basting and relative-juggling are to blame for weight gain, you are not alone. A Google search for ‘stress and weight gain’ reveals a staggering 32,000,000 sites dealing with the topic. However, researchers from our research group have shown that the effect of stress on weight gain may not be as large as you may have thought.

The body tries to maintain stability by adapting to a change in the environment, a process called homeostasis. Stress can be defined as any external factor, physical or psychological, which threatens to throw the body out of homeostasis. Whether running from a hungry lion, or suffering stage-fright before a speech, the body’s response will be the same: the stressor (lion or stage-fright) will trigger the so called ‘fight-or-flight-response’, which is marked by increased heartbeat, muscle-tension, sweating, dilation of the pupils and the release of the ‘stress-hormones’ adrenalin and cortisol. This response is extremely useful to mobilise resources, help us get through difficult situations and regain homeostasis. However, when we experience the on-going stresses of modern life, such as money-worries, job stress, or social pressures, we begin to feel the strain. Long-term stressors overwhelm the body’s coping system, deplete resources and ultimately lead to exhaustion. It has been thought that weight gain results from the body trying to restore homeostasis by inducing metabolic changes which promote fat storage on the one hand and behaviour changes on the other, for example making less time to be active or reaching for cookies instead of carrots.

Results from studies investigating this topic are mixed – some have found that stress has an effect on weight gain, and others have not. Researchers from our department decided to look at the effect from all these studies overall. Summarizing results of several studies on the same topic to find out the ‘true’ effect is called meta-analysis. The studies that were included in this meta-analysis had to be conducted over a period of time (because these are more accurate than studies that only look at a single time-point), measure weight objectively, and focus on external stressors such as life events, work-or caregiver stress. Fourteen studies from Europe and the USA met the criteria; each ‘stress category’ (life events, work- or caregiver stress) was analysed separately.

Results of the meta-analysis showed that stress is related to weight gain, although the effects were very small. When the researchers looked at the results in more depth, they saw that studies that went on for longer and were of better quality were more likely to show an effect of stress on weight. They also saw that the effect appeared to be stronger in men. It did not matter whether the stressor was related to life or work. Unfortunately, eating behaviour was not assessed, so the researchers could not tell whether it changed under stress.

Although there are not very many studies that looked at the topic over a period of time, and imprecise measurements of stress were often used, the findings are relatively robust because of the way the studies were combined. Finding a stronger link of stress on weight in men complements other findings which show that men have a stronger fight-or-flight response. Overall, however, it can be seen that the effects of stress on weight are much smaller than often made out in the media. Blaming the relatives for a bulging belly might be convenient, but complex issues like weight gain unfortunately have no simple, or convenient, answer.